using System;

​

public class Program

{

    //Write a method to count the number of characters in a string

    public static void Main()

    {

        string str = "hh9nuu  kokok";

        int count = 0;

        for (int i = 0; i < str.Length; i++)

        {

            if (Char.IsLetter(str[i]))

            {

                count++;

            }

        }

        Console.WriteLine(count);

    }

}